Electrical equipment is presently being designed with reserve batteries--that is batteries having electrolyte contained in separate storage, which may be released by fracture of the storage ampule. This fracture is accomplished by deforming the battery casing, in an area devoid of electrodes, and when this is done the electrolyte flows to the electrodes and wets them so that the battery is activated to supply its rated voltage and power.
It is customary to design batteries as small right circular cylinders having first ends which fracture an internal ampule of electrolyte when indented. The other ends of the cylinders include first battery terminals, and the cases comprise the other terminals.
Activation of batteries has been performed mechanically, by mechanism which operates to deform the battery directly, but this method requires rather intricate mechanism, does not provide rapid actuation, and often does not result in complete ampule fracture.
Activation of batteries has also been performed explosively. This method involves a pyrotechnic primer located next to the battery, all held by a structural member such as glass-reinforced nylon. A portion of the structural member separates the primer from the battery. The primer deforms or fractures the structural member to activate the battery. This system is sensitive to dimensional tollerances in the structure member, because that member controls the amount of deformation. The structural member interferes with even pressure distribution, so that deformation of the battery case is not uniform, and closer tolerance is required in the amount of explosive and to preclude the presence of voids and air gaps in the explosive to battery interface: a small battery indentation produces poor ampule fracture and slow activation, and a large indentation can produce battery damage. If the structural member fractures, there is the possibility of unintentional loading of the batteries by metallic primer case remnants or explosive residues.